Version number and editing time should be links to view that version. Author's name should not be link. This table does not need a header row.

Each version page should have a link "Show changes"/"Hide changes". When user clicks on "Show changes" then all the text added in that version is displayed on light green background and all the text that was removed is displayed on light red background with strikethrough effect. When user is done with comparing the changes she can click on "Hide changes" link.

Each version page should have button "Revert to that version".

Change History

I agree with Hans design. The simple "show changes" / hide changes" in the version page is enough. No need to compare the changes the "trac style". However, in the version view page we need "save this version" or "edit" button that makes it possible to return the old version.